docs: def _climlab_to_rrtm(field):
      '''Prepare field with proper dimension order.
      RRTM code expects arrays with (ncol, nlay)
      and with pressure decreasing from surface at element 0
  
      climlab grid dimensions are any of:
          - (num_lev,) --> (1, num_lev)
          - (num_lat, num_lev)  --> (num_lat, num_lev)
          - (num_lat, num_lon, num_lev)  -->  (num_lat*num_lon, num_lev)
  
          But lat-lon grids not yet supported here!
  
      Case single column
      '''
      # Make this work just with 1D (KM,) arrays
      #  (KM,)  -->  (1, nlay)
      try:
          #  Flip along the last axis to reverse the pressure order
          field = field[..., ::-1]
      except:
          if np.isscalar(field):
              return field
          else:
              raise ValueError('field must be array_like or scalar.')
      shape = field.shape
      if len(shape)==1:  #  (num_lev)
          #  Need to append an extra dimension for singleton horizontal ncol
          return field[np.newaxis, ...]
      elif len(shape)==2:  # (num_lat, num_lev)
          return field
      elif len(shape) > 2:
          raise ValueError('lat-lon grids not yet supported here.')